US20150243874A1 - Transducers with improved impedance matching - Google Patents

Transducers with improved impedance matching Download PDF

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Publication number
US20150243874A1
US20150243874A1 US14/396,318 US201314396318A US2015243874A1 US 20150243874 A1 US20150243874 A1 US 20150243874A1 US 201314396318 A US201314396318 A US 201314396318A US 2015243874 A1 US2015243874 A1 US 2015243874A1
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transducer
load
piezoelectric device
piezoelectric
overmould
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James East
Neil John Harris
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Google LLC
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NVF Tech Ltd
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Priority to US15/806,823 priority Critical patent/US10714673B2/en
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/88—Mounts; Supports; Enclosures; Casings
    • H01L41/053—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0603—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a piezoelectric bender, e.g. bimorph
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/004—Mounting transducers, e.g. provided with mechanical moving or orienting device
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04—Plane diaphragms
    • H04R7/045—Plane diaphragms using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H10N30/2042—Cantilevers, i.e. having one fixed end

Definitions

  • the following relates to improvements to transducers, also referred to as actuators.
  • FIG. 1 shows an explanatory diagram of an ideal simply supported distributed mode actuator (piezoelectric actuator) 10 ; this is also referred to as a transducer.
  • a piezoelectric resonant element 11 is held in ideal simply supported mounts 12 .
  • the mounts 12 inhibit any translational movement of element 11 in any direction, whist allowing for rotational movement about a point of rotation at the end of the beam. This constitutes an ideal simple support.
  • the transducer is shown mounted to a mechanical ground 13 , and is coupling power or force or velocity 14 into a load which is not shown.
  • FIG. 2 shows an explanatory diagram of an inertial piezoelectric actuator 20 ; also referred to as a transducer.
  • a piezoelectric resonant element 21 is mounted on a coupler 22 .
  • the coupler 22 is itself mounted to the load to be driven 23 .
  • the coupler 22 couples a power or force or velocity 24 into the load 23 .
  • FIG. 3 shows a representation of the velocity and force of a representative transducer as shown in either FIG. 1 or FIG. 2 as a function of load impedance, with the resultant power also shown.
  • a load impedance varies from zero to a maximum (which is infinite), but is here indicated as 1.
  • the velocity of the resonant element of the representative transducer is shown. This has a maximum at zero load impedance and is termed the free velocity. The velocity has a minimum at maximum or infinite load impedance.
  • the force that is provided to the load by the resonant element of the transducer is also shown.
  • the power that is available to be coupled from the transducer to the load is shown, where power is the product of force ⁇ velocity.
  • the desired force, velocity and power is required to be coupled from the transducer to the load impedance over the frequency range of operation of the transducer, which may extend from 50,000 Hz down to effectively 0 Hz, which covers but is not limited to an audio frequency range.
  • the power that can be coupled from the transducer to the load impedance can be thought of as a figure of merit for the transducer, and the problems associated with coupling a transducer to a load may be easily understood when considering the power.
  • transducer applications it is desired to couple a maximum velocity to a load, whereas in some transducer applications it is desired to couple a maximum force to a load. In either or both of these situations it may be desired to couple a maximum possible power to the load available for a particular transducer design thereby minimising the required size of transducer for a particular application.
  • the mechanical impedance of the transducer should be matched to that of the load over the frequency range of interest, which would also result in a relatively smooth variation in power, force and velocity with frequency.
  • FIG. 4 a representation of impedance matching between a load and a transducer is shown, with the resultant power coupled from the transducer to the load also shown.
  • the load and transducer impedances are matched, as represented by the inclined solid line, leading to a maximum power transfer as a function of the available power represented by the horizontal solid line at a power transfer level arbitrarily shown as 1.
  • the maximum amount of available power may be transferred from the transducer to the load.
  • the transducer and load impedances are not matched, for example the transducer impedance is greater than or smaller than the load impedance, then the power transfer can be significantly reduced, for example by an order of magnitude.
  • Transducer and load impedances are frequently not matched over the frequency range of operation leading to reduced power transfer, velocities or forces, and to variations of power, force or velocity that are do not smoothly vary with frequency.
  • the present invention was made in an attempt to solve these problems.
  • transducer having a mechanical impedance over an operative frequency range and having a desired power coupling to a load over the operative frequency range, the transducer comprising;
  • a transducer having an operative frequency range, and having a desired power coupling to a load over the operative frequency range, the transducer comprising;
  • a transducer having a mechanical impedance over an operative frequency range and having a desired power coupling to a load over the operative frequency range, the transducer comprising;
  • a method of manufacturing a transducer having a mechanical impedance over an operative frequency range and having a desired power coupling to a load over the operative frequency range comprising;
  • a transducer comprising;
  • a piezoelectric device in the form of a panel; and a support, the support comprising an elastomeric element and a mechanical ground, the elastomeric element supporting the device at least at a part of the periphery of the device and at least a part of the device extending through the elastomeric element into a recess in the mechanical ground.
  • FIG. 1 shows a schematic diagram of an ideal simply supported piezoelectric actuator.
  • FIG. 2 shows a schematic diagram of an ideal inertial piezoelectric actuator.
  • FIG. 3 shows a representation of the velocity and force of a representative transducer as shown in either FIG. 1 or FIG. 2 as a function of load impedance, with the resultant power also shown.
  • FIG. 4 shows a representation of the power transfer between a transducer characterised by a transducer impedance and a load characterised by a load impedance, showing a representation of load impedance and transducer impedance mismatch
  • FIG. 5 shows the free velocity (with no load impedance) and block force (with infinite load impedance) as a function frequency for an ideal simply supported piezoelectric actuator.
  • FIG. 6 shows the free velocity (with no load impedance) and block force (with infinite load impedance) as a function frequency for an inertial piezoelectric actuator.
  • FIG. 7 shows the velocity as a function of frequency for both an unmodified simply supported and unmodified inertial piezoelectric actuator when driving a load impedance of 5 Ns/m in each case.
  • FIG. 8 shows a schematic diagram of a simply supported piezoelectric actuator modified with impedance matching means.
  • FIG. 9 shows a schematic diagram of an inertial piezoelectric actuator modified with impedance matching means.
  • FIG. 10 shows the velocity as a function of frequency for both the simply supported piezoelectric actuator as shown in FIG. 7 and a non-optimised modified simply supported piezoelectric actuator driving a load impedance of 5 Ns/m in each case.
  • FIG. 11 shows the velocity as a function of frequency for both the inertial piezoelectric actuator as shown in FIG. 7 and a non-optimised modified inertial piezoelectric actuator driving a load impedance of 5 Ns/m in each case.
  • FIG. 12 shows a schematic of an optimised modified simply supported piezoelectric actuator with soft and hard elastomer/polymer impedance matching means.
  • FIG. 13 shows a schematic of an optimised modified inertial piezoelectric actuator with soft and hard elastomer/polymer impedance matching means.
  • FIG. 14 shows the velocity as a function of frequency for both the simply supported piezoelectric actuator as shown in FIG. 7 and the optimised modified simply supported piezoelectric actuator shown in FIG. 12 driving a load impedance of 5 Ns/m in each case.
  • FIG. 15 shows the velocity as a function of frequency for both the inertial piezoelectric actuator as shown in FIG. 7 and the optimised modified inertial piezoelectric actuator shown in FIG. 13 driving a matched load impedance of 5 Ns/m in each case.
  • FIG. 16 shows a schematic diagram of one example of the end mounting for the simply supported piezoelectric actuator shown in FIG. 12 .
  • FIG. 17 shows a schematic diagram of a further example of the end mounting for the simply supported piezoelectric actuator shown in FIG. 12 .
  • FIG. 18 shows the velocity as a function of frequency for the simply supported piezoelectric actuator as shown in FIG. 7 and the optimised modified simply supported piezoelectric actuators shown in FIGS. 16 and 17 driving a load impedance of 5 Ns/m in each case.
  • FIG. 19 shows the velocity as a function of frequency for the simply supported and inertial piezoelectric actuators as shown in FIG. 7 and the optimised modified simply supported piezoelectric actuator as shown in FIG. 17 driving a matched load impedance of 5 Ns/m in each case.
  • FIG. 20 shows a schematic diagram of a further example of the end mounting for the simply supported piezoelectric actuator shown in FIG. 12 .
  • transducer that can be used to couple a desired power to a load.
  • An inertial transducer is a transducer that is not grounded to a frame or other support and is free to vibrate over an extended region such as the region outside its mounting.
  • the resonant element is free to bend and so generate a force via the inertia associated with accelerating and decelerating its own mass during vibration.
  • Inertial transducers may be symmetrical or asymmetrical where symmetrical transducers may be formed by a piezoelectric element supported symmetrically on a central coupler or support and asymmetrical transducers may for example be supported in a cantilever type arrangement.
  • a resonant element of a piezoelectric element of a transducer may have three distinguishable boundary conditions, namely free, clamped (or fixed) and simply supported (or pinned). For the simply supported case, displacement in any axis is prevented but rotation is allowed.
  • a simple support is thus understood as a technical term in acoustical engineering to define the boundary condition of a resonant plate or beam.
  • the plate of the transducer is supported to permit pivotal movement about the support but to prevent translational movement relative to the support.
  • a simple support is thus distinguished from other boundary conditions where the plate is clamped at its edge or where the plate is free at its edge.
  • the benchmark performance for a simply supported, or supported beam, transducer is shown in FIG. 5 .
  • the frequency range of operation is shown varying from 100 Hz to 10,000 Hz.
  • the free velocity (with zero load impedance) is shown on the left vertical axis as a function of frequency, and the block force (with an infinite load impedance) is shown on the right vertical axis as a function of frequency.
  • the free velocity exhibits peaks at approximately 500 Hz and 4500 Hz, with the block force exhibiting a peak at approximately 3000 Hz.
  • the modal and distributed modal behaviour is shown.
  • the benchmark performance for an inertial, or free beam, transducer is shown in FIG. 6 .
  • the frequency range of operation is shown varying from 100 Hz to 10,000 Hz.
  • the free velocity and the block force are again shown as a function of frequency.
  • the modal and distributed modal behaviour is shown.
  • the inertial transducer has a fall off in frequency at low frequencies.
  • the inertial transducer in comparison to the simply supported transducer, exhibits reduced free velocity and block force at low frequencies, but an increased free velocity and block force at higher frequencies.
  • FIGS. 5 and 6 represent the benchmark performance for simply supported and inertial transducers, however in operation transducers are used to drive finite load impedances, rather than zero or infinite impedances.
  • Transducers driving finite impedances are shown in FIG. 7 , where an unmodified inertial transducer and unmodified simply supported transducer are driving a load impedance of 5 Ns/m, and where the velocity of a resonant element of the transducer is shown as a function of frequency. This clearly shows that the simply supported transducer has enhanced output over that for the inertial transducer at low frequencies, with the converse applying at high frequencies.
  • the piezoelectric element for both the unmodified simply supported and unmodified inertial transducer is a bimorph resonant element, meaning that the piezoelectric resonant element is formed from 2 layers of piezoelectric material and can bend in opposite directions.
  • FIG. 8 shows a representation of a modified simply supported piezoelectric actuator or transducer 80 according to an aspect of the invention.
  • An unmodified simply supported piezoelectric actuator 60 has been modified through the use of impedance matching means 81 .
  • the use of impedance matching means 81 could be the application of an additional component or components to the simply supported piezoelectric actuator 60 .
  • the use of impedance matching means 81 could be the substitution of a component part or parts of the simply supported piezoelectric actuator 60 with other component parts.
  • FIG. 9 shows a representation of a modified inertial piezoelectric actuator or transducer 90 according to an aspect of the invention.
  • An unmodified inertial piezoelectric actuator 70 has been modified through the use of impedance matching means 91 .
  • the use of impedance matching means 91 could be the application of an additional component or components to the inertial piezoelectric actuator 70 .
  • the use of impedance matching means 91 could be the substitution of a component part or parts of the inertial piezoelectric actuator 70 with other component parts.
  • the transducer and load impedances may exhibit a mismatch over the frequency range of interest leading to a reduced power transfer, velocity or force characteristic of the transducer. This is because the impedance of the transducer over the frequency range of interest could be different to, and is likely to be different to, the impedance of the load over the frequency range of interest.
  • the load to be driven could have a set impedance or an impedance over a fixed range, for example if a transducer was coupled to the pinna of a person's ear and was being used to excite acoustic vibrations in the pinna to couple sound to the ear in a headphone embodiment.
  • the transducer may need to exhibit certain characteristics which leads to the transducer having a certain impedance or range of impedances over the frequency range of operation.
  • an impedance matching means does not mean that the impedance of the transducer and the impedance of the load are made to be equal over the frequency range of operation or indeed equal over any frequency over the frequency range of operation.
  • Impedance matching refers to a modification of the impedance of the transducer in order that the operation of the transducer over the frequency range of operation is improved, through there being less of an impedance mismatch over the frequency range of operation.
  • the impedance matching means is a means to modify the impedance of the transducer, in order to improve the coupling of power, force or velocity from the transducer to the load.
  • impedance matching means can be thought of as the provision of another degree of freedom within the mechanical impedance space comprising the mechanical impedance of an unmodified transducer and the mechanical of the load, that allows for the designer/engineer of a transducer to drive a load to design a more optimum or optimum transducer to load driving system.
  • the impedance matching means comprises an overmould, for example in the form of a layer, arranged to surround at least part of the piezoelectric device of a transducer.
  • the impedance matching means comprises a soft elastomer that covers at least part of the piezoelectric device.
  • the soft elastomer may be characterised by a Shore A hardness up to 60.
  • the impedance matching means comprises a hard elastomer that covers at least part of the piezoelectric device.
  • the hard elastomer may be characterised by a Shore A hardness up to 90.
  • the impedance matching means comprises a hard polymer that covers at least part of the piezoelectric device.
  • the hard polymer may be characterised by a Shore A hardness up to 100, however typically Shore A hardness applies up to a maximum of 90 and therefore the hard polymer may be characterised by an equivalent Shore D hardness up to 150, but which may typically be up to 100.
  • the applicant has conducted research that has established that care is needed in the application of the impedance matching overmould, because operation of the transducer can be detrimentally affected.
  • FIG. 10 where the velocity of the resonant element of an unmodified simply supported piezoelectric actuator and an incorrectly modified simply supported piezoelectric actuator is shown as a function of frequency when driving a load impedance of 5 Ns/m
  • FIG. 11 where the velocity of the resonant element of an unmodified inertial piezoelectric actuator and an incorrectly modified inertial piezoelectric actuator is shown as a function of frequency when driving a load impedance of 5 Ns/m.
  • Incorrect modification means that the overmould layer has been incorrectly applied, and in the cases shown for the simply supported piezoelectric actuator and inertial piezoelectric actuator are representative of an overmould layer that may be applied if the actuators were to be simply made more robust, for example more able to withstand vibrations or being dropped, without optimising the overmould for impedance matching purposes.
  • FIG. 10 operation of the simply supported piezoelectric actuator is shown where an overmould layer comprising a non optimised soft elastomer layer has been applied around the resonant element of the piezoelectric device, and an overmould layer comprising a non-optimised hard elastomer has been applied to the resonant piezoelectric to form the simple supports.
  • the non-optimised case has been referred to as a na ⁇ ve application, and as shown the performance of the piezoelectric actuator has been severely affected.
  • FIG. 11 operation of the inertial piezoelectric actuator is shown where an overmould layer comprising a non optimised soft elastomer layer has been applied around the resonant element of the piezoelectric device, and an overmould layer comprising a non-optimised hard polymer has been applied around to the resonant piezoelectric to form the coupler between the piezoelectric element and the load.
  • the non-optimised case has again been referred to as a na ⁇ ve application, and as shown the performance of the piezoelectric actuator has been severely affected.
  • the applicant's research has established that the parameters of the overmould layer arranged to surround at least part of the piezoelectric device need to be selected to provide the required impedance matching between the transducer and the load to provide the desired power, velocity and/or force coupling between or from the transducer to the load.
  • the parameters of the overmould to be selected include: the material, which can be a soft or hard elastomer, a rubber material, a polymer material or any other suitable material; the hardness, stiffness, Young's or shear modulus or other material characteristics of the material forming the overmould layer; the thickness of the overmould, especially if the overmould is in the form of a layer, which could vary in thickness at different positions around the piezoelectric layer; and the form of the overmould.
  • the form of the overmould layer refers to: a soft elastomer that surrounds the, or part of the, piezoelectric device: a hard elastomer that surrounds the, or part of the, piezoelectric device and that may provide the simple support means or inertial support means or coupling means between the piezoelectric device and the load, a soft or hard polymer that surrounds the, or part of the, piezoelectric device and that may provide the simple support means or inertial support means or coupling means between the piezoelectric device and the load.
  • the impedance matching means is referred to as an “overmould” because it is particularly convenient for it to be formed by moulding, e.g. injection moulding.
  • moulding e.g. injection moulding.
  • suitable design parameters are not limited to moulded impedance matching means and this disclosure is not to be interpreted as limited to moulded impedance matching means.
  • an overmould e.g. overmould layer
  • an optimised design that comprises a different piezoelectric resonator, different mounting configuration or other different physical aspects to a transducer without an overmould impedance matching means.
  • the overmould impedance matching means in addition to providing impedance matching can provide support or resilience to a piezoelectric element or resonator, meaning that the optimised transducer design with an overmould may not be operable if the overmould was removed and the piezoelectric resonator design did not change.
  • Use of an overmould may allow for the use of an optimised design of piezoelectric resonator that would be fragile, or otherwise not be able to operate or be liable to failure if the overmould was removed.
  • FIG. 12 an example of an optimised simply supported piezoelectric actuator 140 according to an aspect of the present invention is shown in cross section, with overmould impedance matching means.
  • a generally rectangular piezoelectric bimorph 141 in the form of a beam is provided with impedance matching means in the form of a layer of soft elastomer 143 on each of its major surfaces.
  • the elastomer may have a Shore hardness of A30.
  • a suitable thickness for the soft elastomer 143 is 0.5 mm.
  • the piezoelectric bimorph 141 is provided with additional impedance matching means in the form of elastomeric supports 142 .
  • Each of the supports may comprise a hard elastomer for example of Shore hardness A70.
  • Two supports are provided, positioned at either end of the piezoelectric bimorph or resonant element 141 , forming the simple supports or feet for the piezoelectric actuator.
  • the layers of elastomer 143 extend over the entire surfaces of the bimorph up to the supports 142 .
  • the simply supported piezoelectric actuator 140 is mounted to a mechanical ground 13 through the hard elastomer supports or feet 142 , which may have a thickness of 1 mm.
  • the end or periphery of the piezoelectric element 141 terminates within the hard elastomer feet 142 .
  • the feet 142 may be configured to grip a part of the periphery of the piezoelectric element 141 .
  • the feet may extend along the full width of the element 141 .
  • Power 144 is coupled through the soft elastomer layer to a load, not shown but which could for example be the pinna of an ear or a panel of a loudspeaker.
  • the layer of soft elastomer 143 and the hard elastomer feet 142 together form an overmould impedance matching means.
  • FIG. 13 an example of an optimised inertial piezoelectric actuator 150 according to an aspect of the present invention is shown, with alternative overmould impedance matching means.
  • a generally planar piezoelectric bimorph 151 in the form of a beam is surrounded by an overmould impedance matching means in the form of a layer of soft elastomer 153 completely enveloping the bimorph 151 .
  • a suitable Shore hardness for the elastomer is A20.
  • a suitable thickness of the soft elastomer 153 is 0.5 mm.
  • the piezoelectric bimorph 151 is also provided with impedance matching means positioned at the centre of the piezoelectric bimorph or resonant element 151 , forming a coupler 152 from the transducer to the load 23 for the piezoelectric actuator.
  • the coupler 152 may be in the form of a hard polymer coupler 152 of which a suitable Shore hardness is A or D100.
  • the coupler 152 may be shaped to surround a central portion of the bimorph 151 .
  • the inertial piezoelectric actuator 150 is mounted to the load to be driven 23 through the coupler 152 .
  • the soft elastomer of the layer 153 is formed into feet 155 extending between the piezoelectric bimorph 151 and the load 23 .
  • two feet are provided, one at each end of the bimorph, for example positioned 1 ⁇ 3 rd of the way from the end of the piezoelectric bimorph 151 .
  • the feet 155 act as ‘catchers’ and act to support the piezoelectric resonator with the soft elastomer layer 153 .
  • the feet 155 are designed to have a geometry that exhibits flexibility due to the design, allowing the piezoelectric element 151 to vibrate without being restrained or unnecessarily restrained. This allows the optimised design to operate, as discussed above.
  • the position 1 ⁇ 3 rd from the end of the piezoelectric element is an optimum position for feet 155 as would be appreciated by the person skilled in the art from an analysis of the angular momentum of the system.
  • Power 154 is coupled through the hard polymer coupler 152 to a load 23 , which could for example be a panel of a loudspeaker.
  • the piezoelectric elements are generally rectangular but they are not limited to such shapes.
  • FIG. 14 the velocity as a function of frequency of the optimised simply supported piezoelectric actuator of FIG. 12 with an overmould layer is shown alongside the unmodified piezoelectric actuator velocity characteristic as shown in FIG. 7 .
  • the performance of the optimised piezoelectric actuator is significantly better than the non-optimised piezoelectric actuator as shown in FIG. 10 , and is tending toward that of the unmodified piezoelectric actuator.
  • the velocity characteristic is shown, and is tending toward that for the unmodified and at some frequencies has improved upon that of the unmodified, however as discussed above the parameters of the impedance matching means have been selected to provide the required impedance matching between the transducer and the load and accordingly the coupling of power from the transducer to the load will now tend toward that desired or required.
  • FIG. 15 the velocity as a function of frequency of the optimised inertial piezoelectric actuator of FIG. 13 with an overmould layer is shown alongside the unmodified piezoelectric actuator velocity characteristic as shown in FIG. 7 .
  • the performance of the optimised piezoelectric actuator is significantly better than the non-optimised piezoelectric actuator as shown in FIG. 11 , and is tending toward that of the unmodified piezoelectric actuator and indeed improves upon the unmodified at certain frequencies.
  • the velocity characteristic is shown, and is tending toward that for the unmodified piezoelectric actuator and indeed at certain frequencies has improved upon that of the unmodified, however as discussed above the parameters of the impedance matching means have been selected to provide the required impedance matching between the transducer and the load and accordingly the coupling of power from the transducer to the load will tend toward that desired or required.
  • FIG. 16 a schematic diagram of an example of an end mounting for a simply supported piezoelectric actuator 180 according to an aspect of the invention is shown, which shows one end of the simple support of the piezoelectric actuator as shown in FIG. 12 .
  • the simple support means comprises the hard elastomer foot 142 , within which is mounted the end or periphery of the piezoelectric resonant element 141 .
  • a suitable Shore hardness for the foot 142 is 70.
  • a translational stiffness k and a rotational stiffness kr for the element 141 are indicated.
  • a simply supported piezoelectric actuator as discussed above and shown in FIG.
  • the ideal situations for the end of the piezoelectric element 141 to be constrained from translating i.e., the piezoelectric element 141 as shown in FIG. 16 should be constrained from moving in the direction of the extent of the foot as shown.
  • the piezoelectric beam should be free to rotate about a point situated at the end or periphery of the beam or element 141 .
  • k and kr are inextricably linked, and therefore it is not possible to achieve the ideal simple supported mounting configuration.
  • the end mounting configuration shown in FIG. 1 for the ideal simply supported case where simple support mounts 12 are provided to give the ideal simple support, or end mounting means providing one example of an optimised simple support case as shown in FIGS. 12 and 16 can be considered to form a boundary condition for the periphery or end of the piezoelectric device.
  • the parameters of the mounting means can then be selected to provide a required boundary condition for the periphery(s) or end(s) of the piezoelectric device whereby the desired power, force or velocity coupling between the transducer and load is provided.
  • the parameters of the mounting means to be selected include: the material, which can be a soft or hard elastomer, a rubber material, a polymer material or any other suitable material; the hardness, stiffness, Young's or shear modulus or other material characteristics of the material forming the mounting means; the thickness and geometry of the mounting means, and any means for artificially constraining the material forming the mounting means to effectively alter its material characteristics.
  • the material which can be a soft or hard elastomer, a rubber material, a polymer material or any other suitable material
  • the hardness, stiffness, Young's or shear modulus or other material characteristics of the material forming the mounting means the thickness and geometry of the mounting means, and any means for artificially constraining the material forming the mounting means to effectively alter its material characteristics.
  • FIG. 17 shows an example of an end termination of a simply supported piezoelectric actuator, forming a simple support boundary condition.
  • the piezoelectric element 141 is mounted so as to partially extend into a hard elastomer foot 192 .
  • the hard elastomer foot 192 is provided with restraining or constricting means 191 .
  • the restraining means 191 forms a mechanical restraint around the outer periphery of the foot 192 , and inhibits the foot 192 from changing its volume.
  • the restraining means is formed from a non-compliant layer, or applique, that surrounds substantially all of the free surface of the foot 192 .
  • the non-compliant restraining means 191 is formed from a hard polymer or other appropriate material.
  • the elasticity of the restraining means or casing is lower than that of the foot 192 or other mount.
  • the hard elastomer foot 192 (which may be made of rubber) on the sides, and or top, —the material is being inhibited from changing its volume; the high K values shown in the figure create a high value for k.
  • the non-volume-changing rocking motion of the end of the piezoelectric beam 141 activates the low shear modulus values, creating a low value for rotational stiffness kr. This means that by boxing in the hard elastomer foot 192 , the shore hardness of the foot can be reduced from that for an unrestrained foot.
  • the hard elastomer foot now has a Shore A hardness of 40 as opposed to a Shore A hardness of 70 for an unrestrained foot. This has moved the position around which the end of the piezoelectric element 141 rotates from position 183 to position 193 , which means that the rotation position has moved toward the end of the piezoelectric element.
  • the simple support boundary condition has become more like an ideal simple support arrangement.
  • FIG. 18 The result of restraining the hard elastomer foot as shown in FIG. 17 is shown in FIG. 18 where the velocity as a function of frequency for the simply supported piezoelectric actuator with an optimised modified unrestrained hard elastomer foot, for the simply supported piezoelectric actuator with an optimised restrained elastomer foot, and for the unmodified simply supported piezoelectric actuator is shown.
  • the material of the hard elastomer foot from Shore hardness A70 to 40, and boxing-in the sides, an improvement of between 0.1 and 0.9 dB in the response level is obtained in this example, where the improvement may be greater or less than this.
  • the boxing-in or constraining of the mount or foot may be around the sides only but preferably also covers the top as shown.
  • the parameters of the mounting means are selected to provide a required boundary condition that allows the operation of the simply supported transducer to operate in a simply supported mode at low frequencies and effectively in an inertial mode at high frequencies.
  • FIG. 19 shows the velocity as a function of frequency for the simply supported piezoelectric actuator with an optimised modified restrained hard elastomer foot, for the unmodified simply supported piezoelectric actuator and for the unmodified inertial piezoelectric actuator.
  • the simply supported piezoelectric actuator with an optimised modified restrained foot operates as in a simply supported mode at low frequencies, and as shown in this example at frequencies above 2-3000 Hz, it begins to operate in an inertial mode.
  • the hard elastomer feet 142 as shown in FIG. 16 may have a Shore A hardness of 70, but this could be up to 90.
  • the Shear modulus for the hard elastomer may be 2.05 MPa.
  • the piezoelectric bimorph may incorporate a metallic central vane, extended out from the resonant elements, and the hard elastomer feet can be moulded around the vane. Care must however be taken to ensure that the rotation of the end of the piezoelectric element is not constrained. This means that the properties/parameters of the mounting means can be selected to provide the required boundary conditions, to provide the required or desired coupling of power from the transducer to the load.
  • the central vane may be formed from a material other than metal in some examples.
  • FIG. 20 shows the end termination of a simply supported piezoelectric actuator with an extended vane with a hard elastomer around the central vane, and with a soft elastomer overmould over the piezoelectric element.
  • the end termination 210 of one end of a simply supported piezoelectric actuator is shown.
  • Piezoelectric bimorph 211 has a central vane 214 extending out from the piezoelectric materials bonded or attached to either side of the vane.
  • the vane 214 extends all the way through a hard elastomer foot 212 , of an appropriate Shore A hardness that may be up to 90.
  • the hard elastomer foot is mounted to a support mount 215 , which could be mounted to a mechanical ground.
  • the support mount 215 has free space 216 or recess within the part attached to the hard elastomer foot into which the vane 214 extends.
  • the space 216 will modify the characteristics of the hard elastomer foot, and forms one of the parameters that need to be considered when selecting the required parameters for the mounting means as discussed above.
  • the piezoelectric element is also shown with a soft elastomer overmould layer 213 .
  • the frequency range of operation may extend below 100 Hz, tending towards 0 Hz, and may extend above 10,000 Hz to 20,000 Hz, 30,000 Hz, 50,000 Hz and above.
  • the piezoelectric resonant element may be a unimorph, or a bimorph with a central vane.
  • a transducer may be coupled to the panel that forms part of a loudspeaker.
  • acoustic vibrations includes vibrations such as pistonic mode vibrations, bending wave vibrations, resonant bending wave vibrations, and other sound or acoustic vibrations known in the art.
  • the impedance matching means may lead to a reduction in performance at some frequencies over the frequency range of operation.
  • the impedance matching means is applied to the transducer to modify the impedance of the transducer, it is clear that the transducer/load system considered as a whole has had its impedance modified and accordingly, the present invention is considered to cover the modification of the impedance of this whole system.
  • the overmould layer covers substantially all of the piezoelectric device.
  • the overmould layer covers all of the piezoelectric device.
  • the overmould layer covers substantially all of the upper and/or lower surfaces of the resonant element or elements of piezoelectric device.
  • the overmould layer covers all of the upper and lower surfaces of the resonant element of piezoelectric device.
  • the overmould layer has the added advantage over and above that of providing a required impedance matching between the mechanical impedance of the transducer and the mechanical impedance of the load to provide the required or desired power coupling or force coupling or velocity coupling from the transducer to the load.
  • the layer of soft elastomer 143 alone forms the overmould layer to provide the impedance matching means.
  • the hard elastomer feet 142 alone form the overmould layer to provide the impedance matching means.
  • the hard elastomer feet 142 have a different shore A hardness.
  • a stub or coupler may be mounted to the piezoelectric resonant element 141 , on the side of the piezoelectric element 141 opposite to the mechanical ground.
  • This stub or coupler may be used to couple to the load to be driven, such as a panel of a loudspeaker.
  • the stub or coupler may be used to couple to a second piezoelectric element positioned substantially parallel to piezoelectric element 141 in a stacked piezoelectric transducer.
  • the hard elastomer feet 142 could be coupled to the load to be driven rather than to a mechanical ground.
  • velocity or force may be coupled to the load, or velocity and force may be coupled to the load, or power, velocity and force may be coupled to the load.
  • the thickness of the soft elastomer 143 is less than or greater than 0.5 mm, and in other examples the soft elastomer 143 has a Shore A hardness less than or greater than 30.
  • the thickness of the soft elastomer 143 varies across the piezoelectric bimorph 141 .
  • the thickness may be less at the centre of the resonator 141 than at the ends, or the thickness may be greater at the centre than the ends.
  • the soft elastomer 143 is only applied to one side of the piezoelectric bimorph 141 .
  • the hard elastomer feet 142 have a shore A hardness less than or greater than 70, and may have a thickness less than or greater than 1 mm.
  • the piezoelectric element 141 extends one quarter of the way through the hard elastomer feet 142 , or may extend one half of the way through or three quarters of the way through the hard elastomer feet 142 . Other terminating positions are possible.
  • the piezoelectric element 141 extends all of the way through the hard elastomer feet 142 , and the end of the piezoelectric element may be coincident with the outer extent of the hard elastomer feet 142 .
  • the piezoelectric bimorph 141 may extend all the way through the hard elastomer feet, and extend 1 mm, 2 mm or 4 mm out of the other side of a hard elastomer foot 142 . Other extension distances are possible.
  • the layer of soft elastomer 153 alone forms the overmould layer to provide the impedance matching means.
  • the soft elastomer feet 155 alone form the overmould layer to provide the impedance matching means.
  • the hard polymer coupler 152 alone forms the overmould layer to provide the impedance matching means.
  • the coupler 152 may be used to couple to a second piezoelectric element positioned substantially parallel to piezoelectric element 151 in a stacked piezoelectric transducer. In this way there may be more than one additional resonator element making up the piezoelectric actuator transducer, with the overmould layer arranged to surround all or some of this piezoelectric device.
  • the coupler 152 could have a shore A or D hardness greater than or less than 100.
  • the Shore A or D hardness may up to 150.
  • velocity or force may be coupled to the load, or velocity and force may be coupled to the load, or power, velocity and force may be coupled to the load.
  • the thickness of the soft elastomer 153 may be less than or greater than 0.5 mm, and in other examples the soft elastomer 153 has a Shore A hardness less than or greater than 20.
  • the thickness of the soft elastomer 153 varies across the piezoelectric bimorph 151 .
  • the thickness may be less at the centre of the resonator 151 than at the ends, or the thickness may be greater at the centre than the ends.
  • the soft elastomer 153 is only applied to one side of the piezoelectric bimorph 151 .
  • the soft elastomer feet 155 may be at a position other than 1 ⁇ 3 rd the way from the end of the piezoelectric bimorph 151 , such as at the mid point or any other suitable position.
  • the soft elastomer feet 155 may be of a different geometry to that as shown in FIG. 13 if they continue to function as ‘catcher’, as would be appreciated by the person skilled in the art.
  • optimised simply supported piezoelectric actuator as shown in FIG. 13 , there may be more than one the soft elastomer foot 155 along either side of the piezoelectric element 151 .
  • the piezoelectric element 151 may only have one part extending laterally from the support 152 . This means for example that the piezoelectric beam on the right hand side of the coupler 152 may be omitted, the transducer then not being symmetrical.
  • optimised simply supported piezoelectric actuator as shown in FIG. 13 may be symmetrical or asymmetrical (a cantilever type arrangement).
  • a cantilever type arrangement the symmetrical example shown in FIG. 13 may be essentially cut in half—with a piezoelectric element only extending to one side of the support.
  • the frequency responses may look the same, or similar, to that shown for the symmetrical example shown in FIG. 13 , except that there may be only half the blocked-force generated as would be anticipated for symmetrical arrangement.
  • the soft elastomer feet 155 may be omitted.
  • the simple support could be used to mount a touchscreen panel, and/or loudspeaker panel.
  • Such a simple support as described above could be used to mount around the edge or periphery of the touchscreen or loudspeaker panel.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Mechanical Engineering (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Transducers For Ultrasonic Waves (AREA)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10356523B2 (en) 2017-12-13 2019-07-16 Nvf Tech Ltd Distributed mode loudspeaker actuator including patterned electrodes
US10381996B2 (en) 2017-12-20 2019-08-13 Nvf Tech Ltd Active distributed mode actuator
US10477321B2 (en) 2018-03-05 2019-11-12 Google Llc Driving distributed mode loudspeaker actuator that includes patterned electrodes
WO2020002900A1 (en) * 2018-06-25 2020-01-02 Google Llc Actuator for distributed mode loudspeaker with extended damper and systems including the same
US20200177997A1 (en) * 2018-11-30 2020-06-04 Google Llc Reinforced actuators for distributed mode loudspeakers
US10834508B2 (en) 2018-11-30 2020-11-10 Google Llc Reinforced actuators for distributed mode loudspeakers

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201207045D0 (en) * 2012-04-23 2012-06-06 Hiwave Technologies Uk Ltd Transducers with improved impedance matching
JP6524467B2 (ja) * 2015-11-06 2019-06-05 日本特殊陶業株式会社 圧電アクチュエータおよびその製造方法
US10648852B2 (en) * 2018-04-11 2020-05-12 Exo Imaging Inc. Imaging devices having piezoelectric transceivers
CN113808560B (zh) * 2020-06-12 2024-08-02 香港科技大学 基于阻抗匹配的复合超材料的超薄宽频水下吸声器
DE102020121337A1 (de) * 2020-08-13 2022-02-17 Tdk Electronics Ag Piezoelektrischer Wandler und Verfahren zur Einstellung der elektromechanischen Eigenschaften eines piezoelektrischen Wandlers

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2326923A (en) * 1941-09-30 1943-08-17 Rca Corp Art of mounting piezoelectric crystals
US4642511A (en) * 1986-03-31 1987-02-10 Motorola, Inc. Edge-mounting configuration for at-strip resonators
US4736129A (en) * 1985-05-30 1988-04-05 Marcon Electronics Co., Ltd. Ultrasonic motor
US6262517B1 (en) * 2000-02-11 2001-07-17 Materials Systems, Inc. Pressure resistant piezoelectric acoustic sensor
US20070025574A1 (en) * 2003-09-10 2007-02-01 New Transducers Limited Audio apparatus

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11164396A (ja) * 1997-09-25 1999-06-18 Matsushita Electric Ind Co Ltd 圧電スピーカおよびその製造方法
US6307302B1 (en) * 1999-07-23 2001-10-23 Measurement Specialities, Inc. Ultrasonic transducer having impedance matching layer
JP2004518319A (ja) * 2001-01-05 2004-06-17 アー．ヤー． アンゲルセン、ビョルン 広帯域トランスデューサ
JP2006352464A (ja) * 2005-06-15 2006-12-28 Nec Tokin Corp 音響振動発生素子
JP2008061081A (ja) * 2006-09-01 2008-03-13 Kenwood Corp 圧電スピーカ
GB0710378D0 (en) * 2007-05-31 2007-07-11 New Transducers Ltd Audio apparatus
JP2010027500A (ja) * 2008-07-23 2010-02-04 Tdk Corp 有機ｅｌ表示装置及びその製造方法
US8006917B2 (en) * 2008-08-26 2011-08-30 General Electric Company Method and apparatus for reducing acoustic noise in a synthetic jet
CN102265646B (zh) * 2008-12-26 2014-04-23 松下电器产业株式会社 压电扬声器、使用其的压电音响装置以及带警报器的传感器
JP5604096B2 (ja) * 2009-12-25 2014-10-08 東京計器株式会社 液圧システムの圧力保持機構
GB201207045D0 (en) * 2012-04-23 2012-06-06 Hiwave Technologies Uk Ltd Transducers with improved impedance matching
KR102125405B1 (ko) * 2018-08-29 2020-06-22 한국과학기술연구원 넓은 동작 주파수 범위를 갖는 자가 공진 조절 압전 에너지 하베스터
US11482659B2 (en) * 2018-09-26 2022-10-25 Apple Inc. Composite piezoelectric actuator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2326923A (en) * 1941-09-30 1943-08-17 Rca Corp Art of mounting piezoelectric crystals
US4736129A (en) * 1985-05-30 1988-04-05 Marcon Electronics Co., Ltd. Ultrasonic motor
US4642511A (en) * 1986-03-31 1987-02-10 Motorola, Inc. Edge-mounting configuration for at-strip resonators
US6262517B1 (en) * 2000-02-11 2001-07-17 Materials Systems, Inc. Pressure resistant piezoelectric acoustic sensor
US20070025574A1 (en) * 2003-09-10 2007-02-01 New Transducers Limited Audio apparatus

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI712320B (zh) * 2017-12-13 2020-12-01 美商谷歌有限責任公司 包括經圖案化電極之分佈模式揚聲器致動器
US10356523B2 (en) 2017-12-13 2019-07-16 Nvf Tech Ltd Distributed mode loudspeaker actuator including patterned electrodes
US10631089B2 (en) 2017-12-13 2020-04-21 Google Llc Distributed mode loudspeaker actuator including patterned electrodes
US11032643B2 (en) 2017-12-13 2021-06-08 Google Llc Distributed mode loudspeaker actuator including patterned electrodes
US10381996B2 (en) 2017-12-20 2019-08-13 Nvf Tech Ltd Active distributed mode actuator
US10476461B2 (en) 2017-12-20 2019-11-12 Nvf Tech Ltd Active distributed mode actuator
TWI786439B (zh) * 2017-12-20 2022-12-11 美商谷歌有限責任公司 主動分佈模式致動器
US10630253B2 (en) 2017-12-20 2020-04-21 Google Llc Active distributed mode actuator
US10924076B2 (en) 2017-12-20 2021-02-16 Google Llc Active distributed mode actuator
US10477321B2 (en) 2018-03-05 2019-11-12 Google Llc Driving distributed mode loudspeaker actuator that includes patterned electrodes
TWI743497B (zh) * 2018-06-25 2021-10-21 美商谷歌有限責任公司 用於具有延伸阻尼器之分佈式模式揚聲器之致動器及包括其之系統
US11109131B2 (en) 2018-06-25 2021-08-31 Google Llc Actuator for distributed mode loudspeaker with extended damper and systems including the same
US10631072B2 (en) 2018-06-25 2020-04-21 Google Llc Actuator for distributed mode loudspeaker with extended damper and systems including the same
EP4099715A1 (en) * 2018-06-25 2022-12-07 Google LLC Actuator for distributed mode loudspeaker with extended damper, mobile device and system including the same
WO2020002900A1 (en) * 2018-06-25 2020-01-02 Google Llc Actuator for distributed mode loudspeaker with extended damper and systems including the same
US10848875B2 (en) * 2018-11-30 2020-11-24 Google Llc Reinforced actuators for distributed mode loudspeakers
US10834508B2 (en) 2018-11-30 2020-11-10 Google Llc Reinforced actuators for distributed mode loudspeakers
US20200177997A1 (en) * 2018-11-30 2020-06-04 Google Llc Reinforced actuators for distributed mode loudspeakers
US11272289B2 (en) 2018-11-30 2022-03-08 Google Llc Reinforced actuators for distributed mode loudspeakers
US11323818B2 (en) 2018-11-30 2022-05-03 Google Llc Reinforced actuators for distributed mode loudspeakers

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US20180102471A1 (en) 2018-04-12
KR20150048666A (ko) 2015-05-07
EP2841213A1 (en) 2015-03-04
US11730061B2 (en) 2023-08-15
US10714673B2 (en) 2020-07-14
CN104602827B (zh) 2017-10-03
CN104602827A (zh) 2015-05-06
EP2841213B1 (en) 2017-02-01
WO2013160669A1 (en) 2013-10-31
KR102068270B1 (ko) 2020-01-20
JP6293733B2 (ja) 2018-03-14
US20200321511A1 (en) 2020-10-08
JP2015520963A (ja) 2015-07-23
GB201207045D0 (en) 2012-06-06

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